Abstract
An automatic analyzer for ammonia based on the oxydation activity of a reaction product between ammonia and sodium hypochlorite was developed.
The analyzer consists mainly of two parts, a reaction vessel and detection circuit device: Ammonia existing in the air sample is trapped and reacted with sodium hypochlorite in the former, and then is determined by coulometric analysis of the resulted reaction product in the latter.
According to the analytical program settled at a given measurement condition, trapping of ammonia existing in the air sample, its reaction with sodium hypochlorite, transfer of the resulted reaction product to the detection circuit device, electrolysis of free iodine in the coulometric cell and recording of the electrolytic current are all done automatically in the sequence-automatic system.
The lower detection limit was 50 μg/m3 and the measurement range of ammonia was (50-1000)μg/m3 in case of using a 10 liter air sample, and the coefficient of variation of analysis was 1.82% in case of an absorbent solution containing 5 μg of ammonia.
It was further found by an indirect confirmation test that the reaction product between ammonia and sodium hypoclorite was a chloramine-like substance.
